Method of impregnating timber and the like.



U ITED STATES PATENT o EroE.

" ERNST MARMETSCHKE," OF SGHClPFUIt'iH, NEAR EB ERswALnE, GERMANY, ssIGNoR To:

' HEINRICH BRUNING, OF sonoPFU Tn, NEAR ERERsw LnE, GERMANY.

solution of sulfate of iron, common or rock IMETHOD OF IMPREGNATING TIMBER AND THE To all whom it may concern:

Be it .known that I, ERNST MARMETSCHKE, a citizen'of the Empire of Germany, residing at Schopfurth, near Eb'erswalde, Kingdom of Prussia, in the Empire of Germany, have invented a new and useful Method of Impregnating Timber and the Like, of which the followlng is aspecification.

This invention relates to a known process of impregnatingwood and the like under hydrauhc ressure with a mixture of heavy metal sa ts and aluminium com ounds, such as chlorid of zinc or sulfate o cop er and sulfate or acetate of alumina. Hit erto'in such processes it has been proposed to use a salt, cpmmon alum and water which is adually heated to from 80 to 120 C. another process it has been proposed to use a solution containing double sulfate of ammonium with iron,zinc, copper and the like which is first heated to about 60 or 70C. then introduced into a pressure vessel and subsequently heated to 98C.

I have found that a temperature of 100 0..

or more is neither necessary, nor useful, for such temperatures result. in the destruction 'of the mechanical strength of the timber by dissolving the fibers of the'wood. Further,

with such high tem eratures, free mineral acid is formed which also destroys the fiber of the wood unless a neutralizing agent is added to the impregnating solution.

. The present inyention consists in, the application to the impregnating solution, of means for preventing lixiviation' or leaching as for example by the addition of an alumlna compound; then heating the solution to a sufficiently hi h temperature to'produce coagulation of t e albumen of the .wood, but

7 not sufiicient to set .upthe formation of free acid.

The present inventionobviates the difli culties of the former processes and results in Wood completely saturated with the solution of heavy metal salts and aluminium compounds, usingihydraulic pressure,thisresult eing obtained without substantially aiiecting the strength of the wood and without forming more than traces offree mineral acid. To effect this the wood is steeped in the impregnating solution above mentioned under Specification of- Letters Patent.

Application filed May 8, 1907. Serial No. 372,589.

Patented Sept. 8, 1908.

pressure and at a temperature between 60 C. and 98 C.

' The albumen of the wood is coagulated at the minimum temperature mentioned above, this coagulation being essential to the combination of the impregnating substance with the woody fiber which results in a compound insoluble in water and having an antlseptic effect, that is the insoluble combination of the s0lution and fiber sought for is formed at a temperature much less than that supposed to be effective heretofore, with the result that the maximum temperature used by me is below that at which decomposition of the wood fiber will take place, as there is no excessive boilingand no formation of free acid.-

In the present invention the albumen of the wood is coagulated by relatively low.

temperatures ;about 65 O, the wood fiber G can combine with more of the impregnating substances than when using higher temperatures, and at the same time the formation of free acid is avoided.

By trials of the applicant and of the Koe- .nigliches Material PrufiiHgsamtGros'slichterroved that felds near Berlin it has been Wood treated by a solution at t e tenipera tures stated was completely saturated with the impregnating salts while at the same 4 time the formation of the injurious free acid was reduced to'a minimum.

In carrying out the invention the wood to be treated is stripped wholl or partially of its bark and then placed in t e impregnation vessels composed, of iron or the like, after which the vessels are closed hermetically and the air-exhausted from them. The impregnation solution under hydraulic pressure is introduced 1n the vessels composed as above described'of heavy metal salts with the addition of aluminiumsulfate, the wood being wholly immersed in the solution, the temperature ranging from..60 to 98 C. It has been found that three hours is usually-sufii cient for complete impregnation,,.

The novelty of my invention consists in that the wood is'treatedwitha mixture of salts of heavy metals and salts of aluminium in a solution under hydraulic pressure of about 8 to 1'2 kilograms per cubic centimeter and at a temperature between 60 and 98 C. During the heating of the wood in Y the solution combinations of heavy metals ofheavy metals with the addition of an aluand aluminium are formed in the Wood, 'miniulm salt consisting in carrying on theim 10 which are insoluble in water and cause the pregnation at atemperature ranglng between, protectin effect against decay and fire. 60 and 98 C. substantially as described. What claim is: ERNST MARMETSOHKE. The process of preserving Wood which con- Witnesses: sists in impregnating timber and the like un- HENRY HASPER, der hydraulic pressure with a solution of salts WOLDEMAR HAUPT, 

